Hi,
On 18-04-17 15:34, Rafael J. Wysocki wrote:
On Tue, Apr 18, 2017 at 1:54 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
Several Cherry Trail devices (all of which ship with Windows 10) hide the
LPSS PWM controller in ACPI, typically the _STA method looks like this:
Method (_STA, 0, NotSerialized) // _STA: Status
{
If (OSID == One)
{
Return (Zero)
}
Return (0x0F)
}
Where OSID is some dark magic seen in all Cherry Trail ACPI tables making
the machine behave differently depending on which OS it *thinks* it is
booting, this gets set in a number of ways which we cannot control, on
some newer machines it simple hardcoded to "One" aka win10.
This causes the PWM controller to get hidden, which means Linux cannot
control the backlight level on cht based tablets / laptops.
Since loading the driver for this does no harm (the only in kernel user
of it is the i915 driver, which will only use it when it needs it), this
commit makes acpi_bus_get_status() always set status to ACPI_STA_DEFAULT
for the 80862288 device, fixing the lack of backlight control.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Changes in v2:
-Use pr_debug instead of ACPI_DEBUG_PRINT
Changes in v3:
-Un-inline acpi_set_device_status and do the always_present_device_ids
table check inside the un-inlined version of it
Changes in v4:
-Use dev_info instead of pr_debug
-Not only check for ACPI HID but also for CPU (SoC) model so as to not
for devices present on other models then for which the quirk is intended and
to avoid enabling unrelated ACPI devices which happen to use the same HID
Changes in v5:
-Only do the dev_info once per device (acpi_set_device_status gets called
multiple times per device during boot)
Changes in v6:
-Allow specifying more then one CPU-model for a single HID
-Not only match the HID but also the UID, like on Cherry Trail, on some Bay
Trail Windows 10 tablets we need to enable the PWM controller to get working
backlight even though _STA returns 0. The Bay Trail SoC has 2 PWM controllers
and we only need the first one. UID matching will allows adding an entry for
Bay Trail which only enables the first PWM controller
---
drivers/acpi/bus.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++
include/acpi/acpi_bus.h | 6 +----
2 files changed, 66 insertions(+), 5 deletions(-)
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 34fbe02..eb30630 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -34,6 +34,8 @@
#include <linux/reboot.h>
#include <linux/delay.h>
#ifdef CONFIG_X86
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>
#include <asm/mpspec.h>
#endif
#include <linux/acpi_iort.h>
@@ -132,6 +134,69 @@ int acpi_bus_get_status(struct acpi_device *device)
}
EXPORT_SYMBOL(acpi_bus_get_status);
+#ifdef CONFIG_X86
+/*
+ * Some ACPI devices are hidden (status == 0x0) in recent BIOS-es because
+ * some recent Windows drivers bind to one device but poke at multiple
+ * devices at the same time, so the others get hidden.
+ * We work around this by always reporting ACPI_STA_DEFAULT for these
+ * devices. Note this MUST only be done for devices where this is safe.
+ *
+ * This forcing of devices to be present is limited to specific CPU (SoC)
+ * models both to avoid potentially causing trouble on other models and
+ * because some HIDs are re-used on different SoCs for completely
+ * different devices.
+ */
+struct always_present_device_id {
+ struct acpi_device_id hid[2];
+ struct x86_cpu_id cpu_ids[2];
This really is x86-specific, so it should go into somewhere like
arch/x86/kernel/acpi/ or drivers/acpi/x86/ (not present yet).
Ok, but then how do you want to hook this up, before you said
that you wanted to deal with this in acpi_set_device_status(),
which belongs in drivers/acpi/bus.c, do you want the x86
code to provide something like a
bool acpi_device_always_present(struct acpi_device *adev) {
}
Helper function and use that in the drivers/acpi/bus.c
acpi_set_device_status() implementation ?
+ const char *uid;
+};
+
+#define ICPU(model) { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }
+
+#define ENTRY(hid, uid, cpu_models) { \
+ { { hid, }, {} }, \
+ { cpu_models, {} }, \
+ uid, \
+}
+
+static const struct always_present_device_id always_present_device_ids[] = {
+ /*
+ * Cherry Trail PWM directly poked by GPU driver in win10,
+ * but Linux uses a separate PWM driver, harmless if not used.
+ */
+ ENTRY("80862288", "1", ICPU(INTEL_FAM6_ATOM_AIRMONT)),
+};
+#endif
+
+void acpi_set_device_status(struct acpi_device *adev, u32 sta)
+{
+ u32 *status = (u32 *)&adev->status;
+#ifdef CONFIG_X86
+ u32 old_status = *status;
+ int i;
+
+ /* acpi_match_device_ids checks status, so start with default */
+ *status = ACPI_STA_DEFAULT;
+ for (i = 0; i < ARRAY_SIZE(always_present_device_ids); i++) {
+ if (acpi_match_device_ids(adev,
+ always_present_device_ids[i].hid) == 0 &&
+ adev->pnp.unique_id &&
+ strcmp(adev->pnp.unique_id,
+ always_present_device_ids[i].uid) == 0 &&
+ x86_match_cpu(always_present_device_ids[i].cpu_ids)) {
Split this condition please. It is almost unreadable as is.
Not sure what you want me to do here ? Use multiple if's with "continue"
if the check fails, or add whitespace (empty lines) between the conditions,
or ... ?
+ if (old_status != ACPI_STA_DEFAULT)
+ dev_info(&adev->dev,
+ "Device [%s] is in always present list setting status [%08x]\n",
+ adev->pnp.bus_id, ACPI_STA_DEFAULT);
+ return;
+ }
+ }
+#endif
+ *status = sta;
+}
+
void acpi_bus_private_data_handler(acpi_handle handle,
void *context)
{
Thanks,
Rafael
Regards,
Hans
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